CN112786471A - Display panel and method for detecting thickness of display panel - Google Patents
Display panel and method for detecting thickness of display panel Download PDFInfo
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- CN112786471A CN112786471A CN202011644372.XA CN202011644372A CN112786471A CN 112786471 A CN112786471 A CN 112786471A CN 202011644372 A CN202011644372 A CN 202011644372A CN 112786471 A CN112786471 A CN 112786471A
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
- H10K71/10—Deposition of organic active material
- H10K71/12—Deposition of organic active material using liquid deposition, e.g. spin coating
- H10K71/13—Deposition of organic active material using liquid deposition, e.g. spin coating using printing techniques, e.g. ink-jet printing or screen printing
- H10K71/135—Deposition of organic active material using liquid deposition, e.g. spin coating using printing techniques, e.g. ink-jet printing or screen printing using ink-jet printing
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
- H01L22/20—Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
- H01L22/24—Optical enhancement of defects or not directly visible states, e.g. selective electrolytic deposition, bubbles in liquids, light emission, colour change
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
Abstract
The invention discloses a display panel and a method for detecting the thickness of the display panel, and relates to the technical field of display. The thickness detection method comprises the steps that the display panel is divided into a plurality of printing areas, and each printing area is provided with a plurality of display sub-pixels and at least one detection sub-pixel; printing in sequence in a plurality of printing areas along an inkjet printing scan path; before the ink is dried to form a film, emitting ultraviolet light to the detection sub-pixels so that the photoluminescence ink at each detection sub-pixel emits light; collecting the brightness of light emitted by photoluminescent ink at each detection sub-pixel under the excitation of ultraviolet light; and determining the film forming thickness of each detection sub-pixel according to the brightness of the light emitted by the photoluminescence ink at each detection sub-pixel under the excitation of ultraviolet light so as to detect the film forming thickness of the first functional layer in each printing area on the substrate. The invention can quickly obtain the thickness information of the printing area where the detection sub-pixel is positioned according to the film forming thickness of the detection sub-pixel.
Description
Technical Field
The invention relates to the technical field of display, in particular to a display panel and a method for detecting the thickness of the display panel.
Background
The inkjet printing OLED (organic light-Emitting Diode) technology uses a solution ink as a material supply source of an electroluminescent device. The appearance of the solution ink changes when the film is formed, which causes different thicknesses of the film at different positions of the panel.
However, in the conventional method for detecting the thickness of the display panel, after the hole injection layer is printed, the appearance and the film thickness of the substrate at different positions are repeatedly measured by using instruments such as a white light interferometer under experimental conditions, and the process is complex.
Disclosure of Invention
The invention mainly aims to provide a display panel and a method for detecting the thickness of the display panel, and aims to solve the technical problem that the display panel thickness detection method in the prior art is complex in process.
In order to achieve the above object, in a first aspect, the present invention provides a method for detecting a thickness of a display panel, where the method includes:
dividing the display panel into a plurality of printing areas along an ink-jet printing scanning path, wherein each printing area is provided with a plurality of display sub-pixels used for displaying and at least one detection sub-pixel not used for displaying;
synchronously carrying out ink jet printing on the first functional layer ink at all display sub-pixels of each printing area in a plurality of printing areas in sequence along an ink jet printing scanning path, and synchronously carrying out ink jet printing on photoluminescent ink at all detection sub-pixels in each printing area, wherein the photoluminescent ink is consistent with the solvent of the first functional layer ink and comprises a photoluminescent material;
before the first functional layer ink is dried to form a film, emitting ultraviolet light to the detection sub-pixels so that the photoluminescence ink at each detection sub-pixel emits light under the excitation of the ultraviolet light;
collecting the brightness of light emitted by photoluminescent ink at each detection sub-pixel under the excitation of the ultraviolet light;
and determining the film forming thickness of each detection sub-pixel according to the brightness of the photoluminescence ink at each detection sub-pixel emitting light under the excitation of the ultraviolet light so as to detect the film forming thickness of the first functional layer in each printing area on the substrate.
Optionally, determining the film thickness of each detection sub-pixel according to the brightness of the light emitted by the photoluminescent ink at each detection sub-pixel under the excitation of the ultraviolet light, so as to detect the film thickness of the first functional layer in each printing region on the substrate, including:
determining the volume value of the ink at each detection sub-pixel according to the brightness of the light emitted by each detection sub-pixel under the excitation of the ultraviolet light;
and determining the film forming thickness of each detection sub-pixel according to the ink volume value of each detection sub-pixel so as to detect the film forming thickness of the first functional layer in each printing area on the substrate.
Optionally, after determining the film thickness of each detection sub-pixel according to the brightness of light emitted by the photoluminescent ink at each detection sub-pixel under the excitation of the ultraviolet light, so as to detect the film thickness of the first functional layer in each printing region on the substrate, the thickness detection method further includes:
and performing thickness compensation on the thickness abnormal area in each printing area according to the film forming thickness of the first functional layer in each printing area.
Optionally, performing thickness compensation on the abnormal thickness region in each printing region according to the film formation thickness of the first functional layer in each printing region, including:
according to the film forming thickness of the first functional layer in each printing area, when a second functional layer which is arranged in a stacked manner with the first functional layer is formed, thickness compensation is carried out on a thickness abnormal area in each printing area, so that when the first functional layer and the second functional layer are used as a unit, the thickness of the unit is uniform.
Optionally, when forming a second functional layer stacked with the first functional layer according to the film formation thickness of the first functional layer in each printing region, performing thickness compensation on a thickness abnormal region in each printing region, including:
obtaining the film thickness difference between the printing areas according to the film forming thickness of the first functional layer in each printing area;
determining thickness abnormal areas in the plurality of printing areas according to the film thickness difference;
and according to the film thickness difference, when a second functional layer which is stacked with the first functional layer is formed, thickness compensation is carried out on the thickness abnormal area, so that when the first functional layer and the second functional layer are taken as a unit, the thickness of the unit is uniform.
Optionally, the photoluminescent material is configured as an aggregation-induced luminescent material or an aggregation-fluorescence quenching material.
Optionally, the photoluminescent material is tetraphenylethylene or fluorescein.
Optionally, the adjacent detection sub-pixels are arranged at intervals of 500 display sub-pixels.
Optionally, the plurality of print regions comprises:
a first printing area located at a start area of the printing scan path;
a second printing region spaced apart from the first printing region in a column direction;
a third print area spaced apart from the first print area in a row direction and located at an end area of the print scan path;
a fourth print area spaced from the second print area in the line direction and located at an end area of the print scan path; and
a fifth print area located between the first print area, the second print area, the third print area, and the print area.
In a second aspect, the present invention provides a display panel comprising:
a plurality of display sub-pixels for displaying and at least one detection sub-pixel not for displaying, wherein the at least one detection sub-pixel not for displaying is positioned between the plurality of display sub-pixels;
a functional layer having at least a first functional layer and a second functional layer stacked on each other, the thickness of a unit being uniform when the first functional layer and the second functional layer are taken as the unit;
and the area of the first functional layer corresponding to the detection sub-pixel is filled with a photoluminescent material.
According to the technical scheme, part of the sub-pixels in the plurality of sub-pixels in any printing area of the display panel are set as the detection sub-pixels which are not used for displaying, so that when the first functional layer in any area is printed, the photoluminescence ink is synchronously printed at the detection sub-pixels in the printing area. The solvent of the HIL ink is consistent with that of the photoluminescence ink, so that the volatilization conditions of the HIL ink and the photoluminescence ink are consistent. Therefore, the detection of ink volatilization at the sub-pixel can be used for representing the ink volatilization of other display sub-pixels in the part of the printing area. And the photoluminescent ink can emit light with different brightness after being excited by ultraviolet light in solvents with different volumes, and the thickness information of a film formed by the photoluminescent ink in each detection sub-pixel, namely the thickness information of the part of the printing area on the substrate where the detection sub-pixel is located, is quickly obtained according to the brightness of the light emitted by the photoluminescent ink in each detection sub-pixel under the excitation of the ultraviolet light, without repeated measurement by film thickness testing instruments such as a white light interferometer or a step profiler, so that the measurement steps are simplified, and the detection efficiency is improved. And then conveniently form the second functional layer that stacks up with first functional layer at the printing and carry out the compensation of membrane thickness to first functional layer according to the thickness information that detects, obtain the unit that the thickness is homogeneous.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a display panel according to an embodiment of the present invention;
FIG. 2 is a schematic flowchart of a thickness detecting method for a display panel according to a first embodiment of the present invention;
fig. 3 is a flowchart illustrating a method for detecting a thickness of a display panel according to a second embodiment of the present invention.
The reference numbers illustrate:
| reference numerals | Name (R) | Reference numerals | Name (R) |
| 100 | |
200 | |
| 210 | |
220 | Detecting |
| 110 | |
120 | Second printing area |
| 130 | A third printing area | 140 | A fourth printing area |
| 150 | A fifth printing area |
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
In the present invention, unless otherwise expressly stated or limited, the terms "connected," "secured," and the like are to be construed broadly, and for example, "secured" may be a fixed connection, a removable connection, or an integral part; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and/or" appearing throughout includes three juxtapositions, exemplified by "A and/or B" including either A or B or both A and B. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
In contrast to the evaporation process using solid powder organic materials, the inkjet printing OLED technology uses solution-state ink as a material supply source for the electroluminescent device. In the process of performing the inkjet printing process, the ink solvent starts to evaporate slowly after spreading on the TFT substrate, and generally, the ink at the start position of inkjet printing volatilizes the most and the ink at the end position of printing volatilizes the least on the scanning path of inkjet printing according to the difference of the boiling point of the ink and the printing time. Under the same vacuum drying process condition, the difference of the ink volume in the sub-pixels can directly cause the change of the film forming appearance of the film, and the direct reflection is that the thicknesses of the films at different positions of the panel are different. Because the organic functional layer of the OLED device is a thin film with the nanometer thickness, the dispersion of performance indexes such as color coordinates, brightness and the like of the OLED device is large due to the small difference of the thickness of the thin film, and the production yield of the display panel is reduced. In order to control the uniformity of the film thickness, before mass production of the inkjet printed OLED panel, the film thickness is detected, for example, a hole injection layer is printed on a substrate according to a preset process condition, the substrate is taken out after drying and film formation, the appearance and the film thickness of the substrate at different positions are measured by an off-line white light interferometer, a step profiler or other instruments, the process condition is adjusted, an experiment is performed to measure the film thickness again, and the steps are repeated for several times.
For this reason, the technical scheme of the invention sets part of the sub-pixels in the plurality of sub-pixels in any one of the plurality of printing areas of the display panel as the detection sub-pixels which are not used for displaying, so that when the first functional layer in any one of the plurality of printing areas is printed, the photoluminescence ink is synchronously printed at the detection sub-pixels in the printing area. The solvent of the HIL ink is consistent with that of the photoluminescence ink, so that the volatilization conditions of the HIL ink and the photoluminescence ink are consistent. Therefore, the detection of ink volatilization at the sub-pixel can be used for representing the ink volatilization of other display sub-pixels in the part of the printing area. And the photoluminescent ink can emit light with different brightness after being excited by ultraviolet light in solvents with different volumes, and the thickness information of a film formed by the photoluminescent ink in each detection sub-pixel, namely the thickness information of the part of the printing area on the substrate where the detection sub-pixel is located, is quickly obtained according to the brightness of the light emitted by the photoluminescent ink in each detection sub-pixel under the excitation of the ultraviolet light, without repeated measurement by film thickness testing instruments such as a white light interferometer or a step profiler, so that the measurement steps are simplified, and the detection efficiency is improved. And then conveniently form the second functional layer that stacks up with first functional layer at the printing and carry out the compensation of membrane thickness to first functional layer according to the thickness information that detects, obtain the unit that the thickness is homogeneous.
The inventive concepts of the present application are further described below with reference to the following figures and some specific embodiments.
In addition, the present invention provides a first embodiment of a method for detecting a thickness of a display panel, which is used in the display panel. Referring to fig. 2, fig. 2 is a schematic flow chart of a thickness detection method according to a first embodiment of the invention.
In this embodiment, the thickness detection method includes:
step S100, along the scanning path of the inkjet printing, the display panel is divided into a plurality of printing areas, each of which has a plurality of display sub-pixels 210 for displaying and at least one detection sub-pixel 220 not for displaying.
Specifically, the pixels are located on a substrate, which may be a Thin Film Transistor (TFT) substrate having a plurality of pixels arranged in a rectangular array thereon. The pixels on the substrate include a display sub-pixel 210 and a detection sub-pixel 220. The display sub-pixel 210 includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel, so that various colors can be displayed. The detecting sub-pixels 220 are selected partial sub-pixels of the pixels, and the detecting sub-pixels 220 are arranged at intervals, that is, the detecting sub-pixels 220 are interspersed among the displaying sub-pixels 210 and are printed synchronously, so that each detecting sub-pixel 220 can represent the film thickness information of the printing area where the detecting sub-pixel is located.
For example, in one embodiment shown, the plurality of print zones comprises:
a first printing region 110 located at a start region of the printing scan path;
a second printing region 120 spaced apart from the first printing region 110 in the column direction;
a third print region 130 spaced apart from the first print region 110 in the row direction and located at an end region of the print scan path;
a fourth printing area 140 spaced apart from the second printing area 120 in the row direction and located at an end area of the printing scan path; and the combination of (a) and (b),
a fifth print area 150 located between the first print area 110, the second print area 120, the third print area 130, and the print area.
Referring to fig. 1, in the present embodiment, the substrate may be divided into 5 regions, i.e., a first printing region 110, a second printing region 120, a third printing region, a fourth printing region, and a middle region located between the 4 regions. In general, each sub-pixel on the substrate starts from the first printing area 110 of the substrate and ends in the fourth printing area 140 of the substrate during ink jet printing.
In order to represent the film thickness information of different position areas on the substrate, at least one sub-pixel can be selected from the above 5 areas as the detection sub-pixel 220, namely, the first detection sub-pixel 220 of the first printing area, the second detection sub-pixel 220 of the second printing area 120, the third detection sub-pixel 220 of the third printing area, the fourth detection sub-pixel 220 of the fourth printing area, and the fifth detection sub-pixel 220 of the middle area of the substrate. Therefore, when the first functional layer is formed, the thickness information of the corresponding partial area can be represented by each detection sub-pixel 220, and the film thickness information of different position areas on the substrate can be represented.
In some embodiments, adjacent detection subpixels 220 are spaced 500 display subpixels 210 apart from each other.
In this embodiment, since the detection sub-pixel 220 is a sub-pixel of which a part in the sub-pixel array is not used for displaying, carriers in the detection sub-pixel 220 cannot be injected correctly, so that the detection sub-pixel 220 cannot emit light normally. In order to avoid the detection sub-pixels 220 from affecting the display effect of the display panel, the adjacent detection sub-pixels 220 are arranged with 500 display sub-pixels 210 in between. At this time, it is difficult for the naked eye to perceive the presence of the detection sub-pixel 220.
It will be readily appreciated that in order to improve the accuracy of the thickness detection on the substrate, more detection sub-pixels 220 may be provided in the print scan path of the first functional layer.
Step S200, synchronously inkjet-printing a first functional layer ink at all display sub-pixels 210 of each of the plurality of printing areas in sequence along an inkjet-printing scanning path, and synchronously inkjet-printing a photoluminescent ink at all detection sub-pixels 220 of each of the printing areas, wherein the photoluminescent ink is consistent with a solvent of the first functional layer ink, and the photoluminescent ink includes a photoluminescent material.
The first functional layer may be any functional film layer of the display panel, such as a Hole Injection Layer (HIL) or a Hole Transport Layer (HTL), or may be a functional film layer such as an electron transport layer, as long as the functional film layer is formed by inkjet printing, which is not limited in this embodiment.
In some embodiments, a photoluminescent material is included in the photoluminescent material, and the photoluminescent material is configured as an aggregate induced luminescence material or an aggregate fluorescence quenching material.
Specifically, the aggregation-inducing luminescent material has a stronger luminescent intensity when the volume of the solvent is reduced, and may be, for example, tetraphenylethylene. For example, when the first functional layer is a hole injection layer, the hole injection layer has a smaller ink volume and a smaller thickness after being dried and formed in the detection subpixel 220 that emits light with a higher emission intensity when excited by ultraviolet rays, whereas the hole injection layer has a larger ink volume and a larger thickness after being dried and formed in the detection subpixel 220 that emits light with a lower emission intensity.
Alternatively, the photoluminescent material is a focused fluorescence quenching material that reduces in luminescence intensity when the volume of solvent is reduced, and may be, for example, fluorescein. At this time, in the detection sub-pixel 220 emitting light of higher emission intensity when excited by ultraviolet rays, the ink volume of the hole injection layer is large and the thickness is thicker after being dried and formed, whereas in the detection sub-pixel 220 emitting light of lower emission intensity, the ink volume of the hole injection layer is smaller and the thickness is thinner after being dried and formed.
The first functional layer will be specifically described below as an example of a Hole Injection Layer (HIL).
When the display panel is prepared, 1 subpixel point can be selected from 5 printing areas on the substrate and used as the detection subpixel 220.
The printer is provided with a plurality of ink boxes, wherein one ink box is filled with HIL ink, and the other ink box is filled with photoluminescent ink. The two ink cartridges participate in printing at the same time, and both can independently eject ink to designated pixels on the display panel. Thus, when printing the Hole Injection Layer (HIL), the HIL ink is inkjet printed at the display sub-pixel 210 using the cartridge having the HIL ink therein, and the photoluminescent ink is inkjet printed at one or more detection sub-pixels 220 in the display sub-pixel 210 in the area using the cartridge having the photoluminescent ink. At this time, the photoluminescent material in the photoluminescent ink may be fluorescein or tetraphenylethylene.
For example, in inkjet printing the HIL layer to the first printing region 110 on the display panel, the printer prints 50PL of HIL ink to each display sub-pixel 210 within the first printing region 110 while inkjet printing 50PL of photoluminescent ink to the first detection sub-pixel 220 within the first printing region. After ink-jet printing, the ink of all the sub-pixels in the first printing area simultaneously starts to volatilize. And because the solvents of the HIL ink and the photoluminescence ink are consistent, the volatilization conditions of the HIL ink and the photoluminescence ink are consistent. Therefore, detecting the ink volatilization at the sub-pixel 220 can characterize the ink volatilization of other display sub-pixels 210 in the first printing area.
In this way, since the first printing region is close to the printing start position and the fourth printing region is close to the printing end position, the 50PL ink printed in all the sub-pixels in the first printing region has the longest volatilization time and the solvent volatilizes the most, and the 50PL ink printed in all the sub-pixels in the fourth printing region has the shortest volatilization time and the solvent volatilizes the least. Since each region has a corresponding detection sub-pixel 220, it is easy to obtain:
V4＞V3＞V5＞V2＞V1；
where V4 is the ink volume value of the fourth detection sub-pixel 220, V3 is the ink volume value of the third detection sub-pixel 220, V5 is the ink volume value of the fifth detection sub-pixel 220, V2 is the ink volume value of the second detection sub-pixel 220, and V1 is the ink volume value of the first detection sub-pixel 220.
Step S300, before the ink of the first functional layer is dried to form a film, emitting ultraviolet light to the detection sub-pixels 220, so that the photoluminescent ink at each detection sub-pixel 220 emits light under the excitation of the ultraviolet light.
The first functional layer of the display panel may be a Hole Injection Layer (HIL), a Hole Transport Layer (HTL), or a functional film layer such as an electron transport layer, as long as the functional film layer is formed by inkjet printing, which is not limited in this embodiment.
After the inkjet printing is completed and before the ink of the HIL is dried to form a film, the detection sub-pixels 220 are irradiated with UV light so that each detection sub-pixel 220 emits light under excitation of the ultraviolet light.
Step S400, collecting the brightness of the light emitted by the photoluminescent ink at each detection sub-pixel 220 under the excitation of the ultraviolet light.
Specifically, the luminance L of each light can be collected by a silicon photodiode.
Step S500, determining the film thickness of each detection sub-pixel 220 according to the brightness of the light emitted by the photoluminescent ink at each detection sub-pixel 220 under the excitation of the ultraviolet light, so as to detect the film thickness of the first functional layer in each printing region on the substrate.
In this case, the film thickness of the hole injection layer of each detection sub-pixel 220 can be calculated from the luminance L of each light.
Specifically, step S500 includes:
step S501, determining the ink volume value at each detection sub-pixel 220 according to the brightness of the light emitted by each detection sub-pixel 220 under the excitation of the ultraviolet light.
Wherein the ink volume value can be calculated according to the following formula:
L＝a×V+b，
where L is the brightness of the light emitted by the detection sub-pixel 220 under the excitation of ultraviolet light, V is the ink volume value of the photoluminescent ink of the detection sub-pixel 220, and a and b are both constants.
And substituting the acquired brightness L into the formula to obtain the ink volume value V of the corresponding position of the substrate.
Step S502 is to determine the film thickness at each detection sub-pixel 220 according to the ink volume value at each detection sub-pixel 220, so as to detect the film thickness of the first functional layer in each printing area on the substrate.
Here, since the empirical formula V ═ λ · T is obtained for the ink volume value V and the film formation thickness T under the same vacuum drying conditions, and λ is a constant, the film formation thickness T of each detection subpixel 220 can be calculated from the ink volume value V.
For example, under a drying condition of 200torr, the relationship equation between luminance and volume is 15 × V +3, and the empirical equation V is 0.5 × T, and the film thickness T after drying of each detection subpixel 220 is calculated.
At this time, since the detecting sub-pixel 220 and the displaying sub-pixel 210 in any one region print the same volume of ink synchronously, the ink starts to volatilize. The film thickness of the first functional layer, such as a hole injection layer, in the printing region of the detection sub-pixel 220 on the substrate can be reflected according to the film thickness T of the detection sub-pixel 220.
In this embodiment, when the thickness of the HIL layer on the substrate needs to be detected, the detection sub-pixel 220 is formed on the substrate by using a photoluminescent ink including a photoluminescent material, and the photoluminescent ink is consistent with a solvent of the HIL. Therefore, the characteristic that the photoluminescent material can emit light with different brightness after being excited by ultraviolet light in solvents with different volumes can be utilized, the thickness information of the detection sub-pixel 220, namely the thickness information of the printing area where the detection sub-pixel 220 is located, can be quickly obtained according to the brightness of the light emitted by the detection sub-pixel 220 under the excitation of the ultraviolet light, repeated measurement by film thickness testing instruments such as a white light interferometer or a step profiler is not needed, the measurement steps are simplified, and the detection efficiency is improved.
Further, according to the first embodiment of the thickness detection method of a display panel of the present invention, the second embodiment of the thickness detection method of a display panel of the present invention is proposed. Referring to fig. 3, fig. 3 is a schematic flow chart of a thickness detection method according to a second embodiment of the invention.
In this embodiment, after step S500, the thickness detection method further includes:
and S600, performing thickness compensation on the abnormal thickness areas in each printing area according to the film forming thickness of the first functional layer in each printing area.
After the film formation thickness of the first functional layer in each print area is detected, thickness compensation is performed in the subsequent printing process according to the film formation thickness so that the thickness of the unit is uniform when the first functional layer and the second functional layer are used as one unit. Thereby obtaining a display panel with high thickness uniformity. It is worth mentioning that the second functional layer is a functional film layer disposed on top of the first functional layer, for example, when the first functional layer is a Hole Injection Layer (HIL), the second functional layer may be a Hole Transport Layer (HTL). Or when the first function is an electron transport layer, the second functional layer can also be a film structure such as an electron blocking layer. The specific arrangement of the first functional layer and the second functional layer may be specifically arranged according to actual requirements, and the present application is not particularly limited thereto.
Specifically, in this embodiment, the first functional layer whose thickness needs to be detected is HIL, and therefore, when any one of the hole transport layer, the electron injection layer, or the light emitting layer is formed, film thickness compensation can be performed by increasing or decreasing the amount of ink to be printed in a divisional manner. For example, film thickness compensation may be performed at the time of forming the hole transport layer. In this case, step S600 is:
when the hole transport layer of the display panel is formed, thickness compensation is performed on the abnormal-thickness region in the region where each detection sub-pixel 220 is located, according to the film thickness of the HIL layer in each print region.
In this embodiment, step S600 includes:
step S601, obtaining the film thickness difference between the printing areas according to the film forming thickness of the first functional layer in each printing area.
And step S602, determining thickness abnormal areas in the plurality of printing areas according to the film thickness difference.
Step S603, according to the film thickness difference, when forming a second functional layer stacked with the first functional layer, performing thickness compensation on the abnormal thickness region, so that when the first functional layer and the second functional layer are taken as a unit, the thickness of the unit is uniform.
In this embodiment, the second functional layer is a hole transport layer. Specifically, T is obtained by calculation1、T2、T3、T4And T5And then. The film thicknesses of the first, second, third, fourth, and fifth print regions of the substrate can be obtained according to T1、T2、T3、T4And T5The film thickness difference Delta T between the areas of the parts can be calculated, so that the thickness abnormal area needing thickness compensation is determined. The abnormal thickness region may be a region in which the film thickness is greater than the reference film thickness, or may be a region in which the film thickness is less than the reference film thickness. The reference film thickness may be a design film thickness or T1、T2、T3、T4And T5In (1)A number of bits.
Then, when forming a hole transport layer of the display panel, thickness compensation is performed on the thickness abnormal region having a larger thickness by reducing the amount of printing ink. Or when the hole transport layer of the display panel is formed, the thickness of the abnormal thickness area with small thickness is compensated by increasing the amount of the ink, so that the OLED display screen with high film thickness uniformity is obtained.
It will be readily appreciated that in some embodiments, the film thickness compensation may be performed stepwise using a method of divisionally increasing or decreasing the amount of printed ink while sequentially forming a hole transport layer, an electron injection layer, or a light emitting layer.
In addition, the invention also provides a display panel which is prepared by the thickness detection method in the manufacturing process.
In this embodiment, the display panel includes:
a plurality of display sub-pixels 210 for displaying and at least one detection sub-pixel 220 not for displaying, and at least one detection sub-pixel 220 not for displaying is located between the plurality of display sub-pixels 210; and the number of the first and second groups,
a functional layer having at least a first functional layer and a second functional layer stacked on each other, the first functional layer and the second functional layer being formed as a unit, the unit having a uniform thickness;
wherein the area of the first functional layer corresponding to the detection sub-pixel 220 is filled with a photoluminescent material.
The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A thickness detection method of a display panel includes:
dividing the display panel into a plurality of printing areas along an ink-jet printing scanning path, wherein each printing area is provided with a plurality of display sub-pixels used for displaying and at least one detection sub-pixel not used for displaying;
synchronously carrying out ink jet printing on the first functional layer ink at all display sub-pixels of each printing area in a plurality of printing areas in sequence along an ink jet printing scanning path, and synchronously carrying out ink jet printing on photoluminescent ink at all detection sub-pixels in each printing area, wherein the photoluminescent ink is consistent with the solvent of the first functional layer ink and comprises a photoluminescent material;
before the first functional layer ink is dried to form a film, emitting ultraviolet light to the detection sub-pixels so that the photoluminescence ink at each detection sub-pixel emits light under the excitation of the ultraviolet light;
collecting the brightness of light emitted by photoluminescent ink at each detection sub-pixel under the excitation of the ultraviolet light;
and determining the film forming thickness of each detection sub-pixel according to the brightness of the photoluminescence ink at each detection sub-pixel emitting light under the excitation of the ultraviolet light so as to detect the film forming thickness of the first functional layer in each printing area on the substrate.
2. The method for detecting the thickness of a substrate according to claim 1, wherein the determining the film thickness of the first functional layer at each of the detecting sub-pixels according to the brightness of the light emitted by the photoluminescent ink at each of the detecting sub-pixels under the excitation of the ultraviolet light to detect the film thickness of the first functional layer at each of the printing regions on the substrate comprises:
determining the volume value of the ink at each detection sub-pixel according to the brightness of the light emitted by each detection sub-pixel under the excitation of the ultraviolet light;
and determining the film forming thickness of each detection sub-pixel according to the ink volume value of each detection sub-pixel so as to detect the film forming thickness of the first functional layer in each printing area on the substrate.
3. The thickness detection method according to claim 2, wherein after determining the film formation thickness at each of the detection sub-pixels based on the brightness of light emitted by the photoluminescent ink at each of the detection sub-pixels under the excitation of the ultraviolet light to detect the film formation thickness of the first functional layer in each of the printing regions on the substrate, the thickness detection method further comprises:
and performing thickness compensation on the thickness abnormal area in each printing area according to the film forming thickness of the first functional layer in each printing area.
4. The thickness detection method according to claim 3, wherein the thickness compensation for the thickness abnormal region in each print region based on the film formation thickness of the first functional layer in each print region includes:
according to the film forming thickness of the first functional layer in each printing area, when a second functional layer which is arranged in a stacked manner with the first functional layer is formed, thickness compensation is carried out on a thickness abnormal area in each printing area, so that when the first functional layer and the second functional layer are used as a unit, the thickness of the unit is uniform.
5. The thickness detection method according to claim 4, wherein the thickness compensation of the thickness abnormal region among the thickness abnormal regions in each of the printing regions when forming a second functional layer disposed to be stacked on top of the first functional layer in accordance with the film-formed thickness of the first functional layer in each of the printing regions, comprises:
obtaining the film thickness difference between the printing areas according to the film forming thickness of the first functional layer in each printing area;
determining a thickness abnormal area in the plurality of printing areas according to the film thickness difference;
and according to the film thickness difference, when a second functional layer which is stacked with the first functional layer is formed, thickness compensation is carried out on the thickness abnormal area, so that when the first functional layer and the second functional layer are taken as a unit, the thickness of the unit is uniform.
6. The method of claim 1, wherein the photoluminescent material is configured as a concentration-induced luminescent material or a concentration fluorescence quenching material.
7. The method for detecting thickness according to claim 6, wherein the photoluminescent material is tetraphenyl vinyl or fluorescein.
8. The thickness detection method according to any one of claims 1 to 7, wherein adjacent detection sub-pixels are arranged with a distance of 500 display sub-pixels therebetween.
9. The thickness detection method according to any one of claims 1 to 7, wherein the plurality of printing areas include:
a first printing area located at a start area of the printing scan path;
a second printing region spaced apart from the first printing region in a column direction;
a third print area spaced apart from the first print area in a row direction and located at an end area of the print scan path;
a fourth print area spaced from the second print area in the line direction and located at an end area of the print scan path; and
a fifth print area located between the first print area, the second print area, the third print area, and the print area.
10. A display panel, comprising:
a plurality of display sub-pixels for displaying and at least one detection sub-pixel not for displaying, wherein the at least one detection sub-pixel not for displaying is positioned between the plurality of display sub-pixels; and
a functional layer having at least a first functional layer and a second functional layer stacked on each other, the thickness of a unit being uniform when the first functional layer and the second functional layer are taken as the unit;
and the area of the first functional layer corresponding to the detection sub-pixel is filled with a photoluminescent material.
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